This is a multicenter, multinational, randomized, double masked controlled clinical trial in which infants with respiratory insufficiency will be randomly assigned to receive inhaled nitric oxide or to a control group. Entry criteria include any infant requiring assisted ventilation for hypoxic respiratory failure with a diagnosis of PPHN, respiratory distress syndrome, aspiration, pneumonia/sepsis, and suspected pulmonary hypoplasia. There must be two oxygen indices >=15 and <25 with a need of 80% Fi02 via the ventilator. All infants must have an indwelling arterial line. The primary hypothesis is that the use of inhaled Nitric Oxide (iNO) in term/near term infants requiring mechanical ventilation for respiratory failure will decrease the need for Extracorporeal membrane oxygenation (ECMO) from 35% in the control group to 20% in the early iNO group, a relative reduction on 43%. The secondary hypotheses are: 1) Early iNO therapy will reduce the probability of OI's exceeding 25 and receiving subsequent iNO therapy from 60% to 30%. 2) Infants in the early iNO group will, on average, have an increase in their PaO2 levels and a decrease in their mean OI's and AaDO2's measured one hour after administration of study gas, compared to babies in the control group. 3) Early iNO therapy will reduce the number of babies meeting eligibility criteria for ECMO. 4) There will be a decrease in the average length of hospitalization among surviving infants in the early iNO group compared to the control group. 5) The use of early iNO will not increase the following among surviving infants: days of ventilation from randomization, incidence of air leak, incidence of chronic lung disease, and intravascular hemorrhage. 6) There will be no difference in the neurodevelopmental outcome as assessed at 18-24 months corrected age between the iNO treated and control group.